A person invested $810 in an account growing at a rate allowing the money to double every 10 years. How long, to the nearest tenth of a year would it take for the value of
the account to reach $1,690?

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?